Prime Minister John Key is defending the plan that will lock out Aucklanders in favour of unelected directors running more than 75 per cent of services in the Super City.

Mr Key said the business model for running council services was not new, but hinted at changes to make it more accountable to the Auckland Council and ratepayers.

Political heavyweights John Banks and Len Brown, Auckland Chamber of Commerce chief executive Michael Barnett, community leaders and ordinary Aucklanders are opposed to so much activity being run by seven "council controlled organisations".

One submitter to the Government's third and final piece of Super City legislation, lawyer Douglas Allan, said the bill "creates a corporate city, rather than a democratic city".

The biggest concerns are over a CCO which will plan and develop a huge swathe of the waterfront and a mega-CCO for transport that will commandeer about $630 million from Auckland ratepayers to spend on everything from new roads to fixing footpaths.

Mr Key told Newstalk ZB that the Auckland region already had 40 CCOs in operation.

Later, he told the Herald that a select committee was "fine-tuning" the final Super City bill and the Government was following the process closely.

This could signal minor changes strengthening the accountability requirements for CCOs in the legislation, but nothing major like shelving the transport CCO or limiting the waterfront agency to a development role.